docs: def update(self):
          """
          Fetches the updated ring from Redis and updates the current ranges.
          """
          ring = self._fetch()
          n_replicas = len(ring)
          replica_set = set([r[1] for r in self.replicas])
          self.ranges = []
          for n, (start, replica) in enumerate(ring):
              if replica in replica_set:
                  end = ring[(n+1) % n_replicas][0] % RING_SIZE
                  if start < end:
                      self.ranges.append((start, end))
                  elif end < start:
                      self.ranges.append((start, RING_SIZE))
                      self.ranges.append((0, end))
                  else:
                      self.ranges.append((0, RING_SIZE))